At a glance, it seems okay. Android and every app I've seen have many UI flaws, but that's not the X20's fault.

After a week of use, I have to say this is a fantastic phone. It's the perfect beginner's smartphone and there's nothing I've done that's been limited in any way whatsoever by its specifications. I have not run out of storage or memory.. not even close. Do note that I haven't played any games, and I probably never will.

I am really ticked that it doesn't have OTG support, so I can't use the microSD for anything but charging. Powering off, pulling my charging dongle out, removing the half-case, removing the battery cover, removing the battery and moving the CD card back and forth is an awful, awful, way for me to edit files.

An operating system most notably on mobile phones, but also found on media boxes.

Fundamentally flawed - It is tethered to Google in as many ways as they've made possible. From a time server, to internet traffic compression. From google play requiring an account requiring your verified phone number. From hoops to download and install software from their store. It's fucking awful.